Novel dipyrrylmethene dyes

ABSTRACT

Novel dipyrrylmethene dyes, particularly 5 and/or 5&#39;&#39;-odihydroxyphenyl dipyrrylmethene dyes, and 1:1 metal complexes thereof.

United States Patent Bloom et al.

NOVEL DIPYRRYLMETHENE DYES lnventors: Stanley M. Bloom, Waban; PaulinaP. Garcia, Arlington, both of Mass.

Assignee: Polaroid Corporation, Cambridge, Mass.

Filed: April 23, 1968 App]. No.: 723,474

US. Cl. ..260I240.7, 96/3, 96/29 D, 260/ 326.5 J

Int. Cl. ..C09b 23/04 Field of Search ..260I240.7, 326.9

[ 1 Sept. 12, 1972 [56] References Cited FOREIGN PATENTS OR APPLICATIONS562,754 7/ i944 Great Britain ..260/240.7 562,755 7/ l944 Great Britain..260/240.7

Primary Examiner-John D. Randolph AttorneyJohn P. Morley [57] ABSTRACTNovel clipyrrylmethene dyes, particularly 5 and/or 5'- o-dihydroxyphenyldipyrrylrnethene dyes, and l:] metal complexes thereof.

17 Claims, 1 Drawing Figure WAVELENGTH IN M l LLIM ICRONS NOVELDIPYRRYLMETHENE DYES BACKGROUND OF THE INVENTION 3 ,3 ,5 ,5-tetraphenyldipyrrylmethene l 011 l N and a copper complex containingtwo dye molecules to one copper atom has been disclosed in the Journalof the Chemical Society, 1943, page 596.

Metal-complexed dyes such as the aforementioned 2:1 complex generallyexhibit markedly greater stability against the color degradation effectsof actinic radiation, humidity and/or heat than do the non-complexeddyes. However, in certain applications 1:1 complexes are markedlysuperior to 2:1 complexes. For example, 1:] complexes exhibit sharperspectral absorption curves with lesser absorption in unwanted regions ofthe spectrum and hence are of greater value in subtractive colorphotographic systems directed to providing accurate color reproductionsof the subject matter. Moreover, in any uses involving diffusion ortransfer of the dye from one element to another, e.g., in diffusiontransfer color photographic systems wherein an imagewise distribution ofdye is transferred to a dyeable stratum to impart thereto a dye image,the relative mobility of the dye is important and may in fact becritical to practical use of the dye. Obviously, a 2:1 complex(containing two molecules of dye) is considerably more bulky and henceless mobile than a [:1 complex.

The present invention is, therefore, directed to novel dipyrrylmethenedyes which may be employed to obtain [:1 metal complexes, unlike thepreviously disclosed tetraphenyldipyrrylmethene, and to 1:1 metalcomplexes obtained therefrom. Simply stated, the present invention isdirected to novel analogues of the previously disclosed3,3'-5,5'-tetraphenyldipyrrylmethene, which analogues will provide 1:]complexes as distinguished from the previously disclosed dye which willonly provide 2:] complexes.

SUMMARY OF THE INVENTION The novel dyes of this invention may be definedas being dipyrrylmethenes containing an o-hydroxyphenyl radical, i.e.,o-hydroxyphenyl or an o-hydroxyphenyl radical containing substituentsbonded to other nuclear carbon atoms, in at least one of the 5 and 5'positions. The novel metal-complexed dyes of this invention are H metalcomplexes of the above-mentioned dyes. The complexes may further includeany ligand, preferably a non-chromophoric ligand, if necessary tosatisfy the coordination number of the particular metal employed to formthe complex, as is common to the art of forming dye complexes generally.

BRIEF DESCRIPTION OF DRAWING The FIGURE is a graphic illustrationcomparing the spectrophotometric curve of a typical magenta dye of thisinvention with two other magenta dyes.

DESCRIPTION OF PREFERRED EMBODIMENT In the preferred embodiment, thenovel 1:] metal complexes are complexes of a transition metal, e.g., Cr,Mn, Fe, Co, Ni, Cu, Ru, Rd, Pd, Pt, Ag, lr, Au, etc., although metalsother than the transition metals, e.g., Cd, Zn, Mg, etc. are alsocontemplated.

As was mentioned previously, this invention relates to noveldipyrrylmethene dyes and to [:1 metal complexes of such dyes.

A primary object of this invention, therefore, is to prepare novelnon-complexed dyes of the foregoing description.

Another object is to prepare novel lzl metal complexes of such dyes.

Still another object is to provide novel intermediates for use inpreparing the novel dyes of this invention.

Other objects of the invention will in part be obvious and will in partappear hereinafter.

The invention accordingly comprises the several steps and the relationand order of one or more of such steps with respect to each of theothers, and the product processing the features, properties and therelation of elements which are exemplified in the following detaileddisclosure, and the scope of the application of which will be indicatedin the claims.

For a fuller understanding of the nature and objects of the invention,reference should be had to the following detailed description taken inconnection with the accompanying drawing.

The novel dipyrrylmethene dyes of this invention containing a 5 and/or5'-o-hydroxyphenyl radical may be represented structurally by thefollowing formula:

(A) R R wherein: each R, which may be the same or different, may bealkyl of one to 18 carbon atoms, preferably one to six carbon atoms,aryl, e.g., phenyl or naphthyl, substituted aryl, e.g., a phenyl ornaphthyl nucleus containing one or more of the following substituents:hydroxy, chloro, methyl, ethyl, methoxy, ethoxy, C0Ol-l, CONH etcs,

Q may be an alkyl of one to six carbon atoms, preferably less than fourcarbon atoms, i.e., methyl, ethyl, propyl, or isopropyl, anN,N-dimethylaminoalkyl, N,N-diethylaminoalkyl or N-methyl, N-ethylaminoalkyl wherein the alkyl moiety contains one to six carbonatoms, preferably less than four carbon atoms,

each 2, which may be the same or different, may by hydroxy, chloro,alkoxy, preferably lower alkoxy containing one to six carbon atoms,e.g., methoxy, ethoxy, etc.; alkyl, preferably lower alkyl containingone to six carbon atoms, e.g., methyl, etc., carboxy or amido;

m is a positive integer from 1-4, it being understood that where m is I,each of the carbon atoms of the benzene nucleus is unsubstituted, i.e.,contains a hydrogen atom; and

X is hydrogen or hydroxy, provided that where Q does not comprise ano-hydroxyphenyl or substituted o-hydroxyphenyl, as heretofore described,X must be hydroxy.

The preferred dyes of formula A are those within the following formula:

wherein each R, which may be the same or different, is methyl, ethyl,phenyl or a substituted phenyl of the formula:

on f I! 11 N/ UQQ Clh

(lily i u I on it will be noted that compounds 14 and I are dyedevelopers. that is dyes which are also silver halide developing agents,the developing function in this instance being supplied by thep-dihydroxyphenyl moiety. in addition to being capable of beingcomplexed to provide a 1:1 metal complex, the dyes of compounds [4 andare thus of separate utility in the photographic systems for preparingcolor images described and claimed in US. Pat. No. 2,983,606 issued toHoward 0. Rogers. In such systems, a

v function of development to provide an image-wise distribution ofdiffusible dye which is transferred, at least in part, by diffusion. toa superposed dyeable stratum to impart thereto a dye transfer image.

It will be appreciated, however, that if the dye is first complesed, thedeveloping function is effectively removed so that a metal complex of adye of formulas l4 and 15 may not be employed as a dye developer in suchsystems.

The dyes of formulas l6 and I? are also dye developers. However, it willbe observed that the developing function is contained on a differentportion of the molecule so that a metal complex of these dyes may beemployed as a dye developer in the foregoing patented system. The metalcomplex may be formed prior to color image formation, in which case itis employed in the manner described in the aforementioned patent and in[15. Pat. No. 3,2l8,l64 issued to Milton Green, et al., or it may becomplexed after color image formation to increase the stability againstfading of the thus formed color print. In like manner, non-complexed dyedevelopers such as those of formulas l4 and 15 may be employed toprovide color transfer images which can be completed after imageformation. The after-complexing of dye transfer images is described, forexample, in US. Pats. Nos. 3,08l,l67 and 3,196.0.

The novel dyes of this invention may be made by condensing a pyrrole ofthe formula:

with a. fi-tormylpyrrole of the formula:

R ia." N x A or by condensing a pyrrole of the formula:

with nitromethane to form a compound of the formula:

followed by hydrogenation in the presence of a suitable hydrogenationcatalyst. e.g., Raney nickel, to effect reduction, ring-closure, anddehydrogenation to form the desired compound of formula C. However,where 0 comprises a hydroxyphenyl substituent, the starting compound offormula G preferably employs the protected methoxy analogue, in whichevent the corresponding methoxyphenyl pyrrole is formed. To obtain thedesired hydroxyphenyl compound, i.e., a pyrrole of formula C wherein 0comprises a hydroxyphenyl substituent, the methoxyphenyl analogue isthen demethylated by known demethylation techniques, e.g., by reactionwith boron tribromide.

The compounds of formula F may be obtained by the same procedure, namelyby reacting a vinyl ketone of the formula:

with nitromethane to form a compound of the formula:

m t: It

TW I awn-Q ti (1 (ill It followed by hydrogenation, ring closure anddehydrogenation in the manner described above. Again, where X isintended to be hydroxy, the methoxy analogue is first prepared, followedby demethylation as described above.

The S-formyl compounds of formula D may be prepared by reaction of acompound of Formula F with dimethylformamide and P0C1 In like manner the5- formyl compounds of formula B may be prepared by the same reaction ofa compound of Formula C.

In the aforementioned reactions, potassium cyanide may be employed inlieu of nitromethane, if desired.

Where the compounds of formula A are symmetrical, i.e., where bothpyrrole moieties contain the same substituents, they may be prepared byreacting a compound of formula C or a compound of formula F with formicacid or a derivative:

RCHO

to form the desired compound of formula A. They may also be prepared byreacting a compound of formula C with HC(0C H or an aromatic carboxylicacid, e.g., benzoic acid.

The compounds of formula C and E wherein Q is odihydroxyphenyl or asubstituted o-dihydroxyphenyl and the compounds of formulas D and Fwherein X is hydroxy are themselves novel compounds, as are the methoxyanalogues thereof as noted above.

Metal complexes of the novel dyes of this invention may be prepared inthe manner common to the art of dye complexing, namely reacting the dyewith a metal salt, e.g., an organic salt. This may be accomplished, forexample, by refluxing a solution of the reactants for the requisitetime. The resulting complex may be readily recovered from the reactionmixture by conventional techniques, e.g., filtration. Where necessary tosatisfy the coordination number of the metal employed, a ligandproviding the requisite number of coordinating atoms, Le, a uni-dentateor multi-dentate ligand, will be required to form the l:l complex, aswill be ap- EXAMPLE 1 To a well-stirred solution of 33.6 g. (0.84 mole)of sodium hydroxide in 302 g. of water and [54 g. of ethanol was addedg. (0.66 mole) of Z-methoxyacetophenone under a nitrogen atmosphere at15 C. Seventy-five grams (0.66 mole) of benzaldehyde was added to themixture, after which it was stirred at room temperature for l2 hours inan inert atmosphere. At the end of such time, the mixture was extractedwith three ZOO-ml. portions of ether. The combined ether extracts werewashed with two l00-ml. portions of water, dried over anhydrousmagnesium sulfate, and concentrated by flash evaporation. Subsequentdistillation of the residual liquid in vacuo afforded 108.3 g. (68.8percent) of 2-methoxy chalcone, b.p. l446 C/0.04 mm. (m.p. 389 C)(Found: C, 81.29; H, 6. l 4, C H O requires C, 80.60; H, 5.98) To amixture of I083 g. (0.45 mole) of 2-methoxychalcone (prepared as above)and 30.8 g. (0.42 mole) of nitromethane in 566 ml. of anhydrous methanolwas added a methanolic solution of sodium methoxide, prepared from 1 L5g. of sodium and I42 ml. of anhydrous methanol, over a period of 40minutes under a nitrogen atmosphere at a temperature of about 38 C. Themixture was stirred at room temperature for the next 2 hours, afterwhich it was neutralized with glacial acetic acid and then chilledovernight. The off-white solid was removed by suction filtration andrecrystallized once from ethanol. There was obtained 90.5 g. (66.2percent) of 'y-nitrofi-phenyl-2-methoxybutyrophenone, m.p. 9l2 C.(Found:

C,68.20; H,5.87; N, 4.81 c,,H,,No, requires C, 68.30; H, 5.70; N, 4.68.)One hundred and forty grams (0.47 mole) ofy-nitro-fiphenyl-Z-methoxybutyrophenone (prepared as above) and Raneynickel, in 500 ml. of ethyl acetate was allowed to absorb hydrogen in aParr shaker at room temperature until the theoretical uptake had beenreached. The catalyst was removed by filtration and washed with smallportions of ethyl acetate. The solvent was removed by flash evaporationand the residual oil was completely dehydrated on a steam cone atreduced pressure overnight. The resulting brown oil and 50 g. of 30 percent palladium or carbon was refluxed with 1.5 l. of p-cymene for 24hours. The catalyst was removed by filtration and washed with smallportions of p-cymene. The combined filtrate and washings wasconcentrated to 200 ml. during which time the crude product separated.One recrystallization of this crude product from ligroine, b.p. 90-l20C., afforded 47 g. (40 percent of 2-o-anisyl-4-phenylpyrrole, m.p. l-6C. (Found: C, 8.05; 1-1, 5.96; N, 5.66. C HL-SNO requires C, 81,861 H,6.08; N, 5.63.) U. V. A 241 (622,800) A m 316(e 15,200). To a solutionof 47.0 g. (0.19 mole) of 2-o-anisyl-4- phenyl-pyrrole in 450 ml. ofanhydrous methylene chloride was added 148 g. (0.59 mole) of borontribromide with stirring over a period of 1 hour. Stirring at roomtemperature was continued for an additional 6 hours. At the end of thistime, 90 ml. of methanol and 216 ml. of percent hydrochloric acid wasadded dropwise in succession to the reaction mixture. The methylenechloride layer was separated, washed thoroughly with water, and thendried over anhydrous magnesium sulfate. The solvent was removed by flashevaporation and the residue was purified by boiling its methanolicsolution with Norit A. Subsequent removal of methanol by slowevaporation and extraction of the residue with boiling ligroine, b.p.90l20C., gave 21.0 g. (47 percent) of 2-o-hydroxyphenyl-4-pheny1pyrrole,m.p. l27.5-l29 C. (Found: C, 82.12; H, 6.20; N, 5.80. C H NO requires C.81.60; H, 5.68; N, 5.96.) U. V. A An abbreviation for methyl cellosolve,i.e., B-methoxyethanol.) 242 My (22,000); A 278 My (14,800) A 318 My.(18,200). A mixture of 5.0 g. (21.0 mM) of2-o-hydroxyphenyl-4-phenylpyrrole and 5.0 g. (20.0mM) of2,4-diphenyl-5-formylpyrrole in 300 ml. of anhydrous methanol wastreated with short bursts of dry hydrogen chloride at about 25 C. untilno further precipitation of the green solid was observed. The reactionmixture was stirred for an additional 3 hours and then chilled. Thecrude dye mixture was removed by suction filtration, washed with smallportions of cold methanol, and then ether. There was obtained 10.0 g. ofcrude dye, m.p. 21 l-2l 4 C. Ten grams of the dye mixture in 1.3 l. ofmethylene chloride was treated with 50 ml. of triethylamine. Theresulting solution was chromatographed on 4.8 X 40 cm. column of Woelmneutral alumina. Continuous elution of the column with methylenechloride gave the first fraction, which yielded 1.30 g. 13.8 percent) of3,3, 5,5'-tetraphenyldipyrrylmethene, m.p. 284286 C. Mixed melting pointwith an authentic sample showed no appreciable depression. Thechromatogram was extruded and then extracted with methanol-methylenechloride (1:20) until most of the dye base had been removed. The extractwas evaporated to dryness in vacuo. Two recrystallizations of theresidue from nitrobenzene afforded 6.0 g. (68 percent) of3,3,5'-triphenyl-5-ohydroxyphenyldipyrrylmethene, the compound of formula l, m.p. 260-l C. A 542 My; e=44,000 C=l.8 X 10" M (Found: C, 85.75;H, 5.12; N, 6.16; O, 3.45 C H N O requires C, 85.40; H, 5.20, N, 6.03;O, 3.45.)

EXAMPLE 2 3,3-Dipheny1-5,5'-di-(o-hydroxyphenyl) dipyrrylmethene (111).A mixture of 5.0 g. (21.0 mM) of 2-0- hydroxyphenyl-4-phenylpyrrole, 40ml. of formic acid (97 percent-100 percent). and 10 ml. of hydrochloricacid (sp. gr. 1.19) was refluxed for 12 hours, after which it waschilled. The crude product was removed by suction filtration, washedwith ether, and then boiled with 200 m1. of methanol containing 5 ml. oftriethylamine for 15 minutes. The crude dye base, which separated oncooling, was recrystallized twice from pyridine-methanol 1:4). There wasobtained 4.5 g. (88 percent) of 3,3'-diphenyl-5,5'-di-(o-hydroxyphenyl)dipyrrylmethene, the dye of formula 2, m.p. 268-9 C. A 556; $47,800C=1.8 X 10' M (Found: c,82.85; H, 5.07; N, 5.71',O, 6.62. C H N O 2 3C,82.50; 11.5.04; N,5,83;O, 6.66.)

EXAMPLE 3 To a well-stirred solution of 100 g. (0.67 mole) of 2-methoxyacetophenone and 40 g. (0.91 mole) of acetaldehyde in 200 ml. ofanhydrous methanol was added 64 ml. of methanolic sodium methoxide,prepared from 3.2 g. of sodium metal and 64 ml. of anhydrous methanol,at about 10 C. over a period of 1 hour. After addition was complete, themixture was stirred at 5-l0 C. for the next 20 hours. At the end of thistime, glacial acetic acid was added dropwise until the solution wasneutral. The solvent was removed by distillation and the residual liquidwas diluted with 250 ml. of water and then extracted with three -m1.portions of ether. The combined ether extracts were dried over anhydrousmagnesium sulfate and concentrated on a flash evaporator until thesolvent had been removed. Subsequent distillation of the residual oil invacuo gave 27.6 g. of a pale yellow oil, b.p. I38-l40 C/mm. Assay byvapor phase chromatography showed the oil contained 42.2 percent of3-(o-anisyl)-propene-2 and 47.0 percent ofB-methoxy-o-methoxybutyrophenone. Twenty-seven grams of the foregoingmixture and 0.3 g. of freshly fused, finely pulverized zinc chloridewere heated at an oil bath temperature of l50-l60 C. and an internalpressure of 100 mm. until all the methanol had been eliminated. Theresidual mixture was cooled to room temperature, acidified with 50 m1.of 3 percent acetic acid, and then extracted with two 100-ml. portionsof ether. The combined ether extracts were washed with water, dried overanhydrous magnesium sulfate, and concentrated on a flash evaporator.Subsequent distillation of the residual oil in vacuo gave 10.3 g. of3-(o-anisyll-propene-2, b.p. 87-9 C./0.05 mm. Assay by vapor phasechromatography showed the distillate was 96 percent pure. To awell-stirred mixture of 5.3 g. (0.03 mole) of 3-(o-anisyl)-propene-2(prepared as above and 1.8 g. (0.03 mole) of glacial acetic acid in 40ml. of ethanol was added 3.9 g. (0.06 mole) of potassium cyanide in 10ml. of water over a period of 10 minutes at 35-40 C. After addition wascomplete, the reaction mixture was stirred at this same temperature foran additional 3 hours. The mixture was chilled and the crude product wasremoved by suction filtration and washed with water. Onerecrystallization from ethanol gave 3.0 g. (49.3 percent) ofB-cyano-omethoxybutyrophenone, m.p. 63-4 C. Found: C, 70.85; H, 6.40; N,6.96; O, 15.81. C H NO, requires C, 70.90; H, 6.45; N, 6.90; O, 15.80.Forty-seven grams (0.23 mole) of B-cyano-o-methoxybutyrophenone andRaney nickel in 200 ml. of ethyl acetate was allowed to absorb hydrogenin a Parr shaker at room temperature until the theoretical hydrogenuptake had been reached. The catalyst was removed by filtration andwashed with small portions of ethyl acetate. The solvent was removed byflash evaporation and the residual oil was completely dehydrated on asteam cone at reduced pressure overnight. There was obtained 35.0 g. ofan isomeric mixture of crude pyrroline. The foregoing mixture (35.0 g.)and 8.0g. of 30 percent palladium on carbon in 200 ml. of p-cymene wasrefluxed for 2 hours under a nitrogen atmosphere, after which thecatalyst was removed by filtration and washed with small portions ofp-cymene. The solvent was removed by flash distillation and the residualliquid was distilled in vacuo. There was obtained 13.? g. (31.8%) of2-0- anisoyl-4-methylpyrrole, b.p. l05-7 C./ 0.05 mm. Found: C, 76.85;H, 6.83; N, 7.43; 0, 8.36. C H NO requires C, 76.95; H, 7.00; N, 7.48;O, 8.55. UV )t 289 Mp. (13,000); A 310 My. (el4,000). To a well-stirredsolution of 14.0 g. (0.075 mole) of 2- o-anixoyl-4-methylpyrrole in 150ml. of dry methylene chloride was added 45.2 g. (0.18 mole) of borontribromide over a period of 40 minutes. After addition was complete themixture was stirred at room temperature for 6 hours. At the end of thistime, 50 ml. of methanol and 100 ml. of 10 percent hydrochloric acid wasadded in succession. The reaction mixture was stirred at roomtemperature for I hour, after which it was extracted with four 75-ml.portions of methylene chloride. The combined extracts were washedthoroughly with water, dried over anhydrous magnesium sulfate, andevaporated to dryness in a flash evaporator. Subsequentrecrystallization from ligroine (b.p. 90-l20 C.) and decolorization withNorit gave 3.3 g. (25.4 percent) of 2-o-hydroxyphenyl-4-methy1pyrrole,m.p. 83-4 C. Found: C, 76.26; H, 6.34; N, 8.05; O, 9.45.

C H NO requires C, 76.25; H, 6.43; N, 8.08; O, 9.25UV It 285 Mp.(12,200) )t,,,,,,'" 315 Mp.( $12,600). A mixture of 2.6 g. 15.0 mM) of2-0- hydroxyphenyl-4-methyl-pyrrole and 1.85 g. (15.0 mM) of2,4-dimethyl-5-formylpyrrole in 60 ml. of anhydrous methanol was treatedwith short bursts of anhydrous hydrogen chloride at about 2540 C. untilno further precipitation was observed. Subsequent chilling gave thecrude dye, which was removed by suction filtration and washed with coldmethanol, basified with triethylamine, boiled on a steam bath for [0minutes and then chilled. One recrystallization of the resulting dyebase from methanol-triethylamine gave 3.0 g. (72%) of5'-o-hydroxyphenyl-3,3,5-trimethyldipyrrylmethene, the compound offormula 3, mp. l245 C. A (MeCell) 490 M e 42,800; Elemental Analysis:Calc. C. 77.60; H, 6.54: N, 10.08; 0, 5.75; Found: C, 77.1 1; H, 6.73;N, 9.65; O, 5.63.

EXAMPLE 4 A mixture of 0.5 g. (2.9 mM) of 2-o-hydroxyphenyl-4-methylpyrrole, 5.0 ml. of formic acid (99-100 percent) and 10 drops ofhydrochloric acid (sp. gr. 1.19)

was refluxed for 1.5 hours, after which it was cooled and stirred with35 ml. of ether. The precipitate was removed by suction filtration,washed thoroughly with ether and recrystallized once frommethanoltriethylamine. There was obtained 0.30 g. (75.0 percent) of3,3'-dimethyl-5,5'-di-o-hydroxypheny|-dipyrrylmethene, the compound offormula 4, mp 224-5 C. A... (MeCell) 536 mu; e 48,300; ElementalAnalysis: Calc. C, 77.60; H, 5.68; N, 7.87; O, 8.95; Found: C, 77.68; H,5.76; N, 7.67; 0, 8.86.

EXAMPLE 5 A mixture of 4.7 g. (20.0 mM) of2-o-hydroxyphenyl-4-phenylpyrrole and 2.46 g. (20.0 mM) of 2,4-dimethyl-S-formylpyrrole in ml. of anhydrous methanol was treated withshort bursts of anhydrous hydrogen chloride at about 25-30 C. until nofurther precipitation was observed. Subsequent chilling gave the crudedye, which was removed by suction filtration and washed with coldmethanol. This crude dye was suspended in 70 ml. of methanol, basifiedwith triethylamine, boiled on a steam bath for 10 minutes and thenchilled. One recrystallization of the resulting dye base frommethanol-triethylamine gave 6.0 g. (88.5 percent) of5'-o-hydroxyphenyl-3'-phenyl-3,5- dimethyldipyrrylmethene, the compoundof formula 5, mp 167-- C. A, (MeCell) 495 mu: 42,800; ElementalAnalyses: Calc. C, 81.10; H, 5.94; N, 8.24; 0, 4.71; Found: C, 80.40; H,6.09; N, 8.35; O, 4.98.

EXAMPLE 6 A mixture of 0.50 g., (1.0 mM) of 3,3',5,5'-tetraphenyldipyrrylmethene and 0.30 g. l .4 mM of zinc acetate dihydratewas refluxed with 25 ml. of n-butanol for one hour, after which it waschilled. The precipitate was removed by suction filtration, washed withsmall portions of methanol, and recrystallized once frompyridine-methanol. There was obtained 0.50 g. (93 percent) of the 2:1zinc complex of 3,3',5,5'-tetraphenyldipyrrylmethene m.p. 293-4 C. A 529p; c 110,000 C=1.8 10" M (Found: C, 82.70; H, 4.84; N, 5.96; Zn, 6.77 CH,,N,Zn requires C, 82.52; H, 4.83; N, 5.83; Zn. 6.81.)

EXAMPLE 7 A mixture of 0.51 g., 1.1 mM) of5'-o-hydroxyphenyl-3,3',S-triphenyl-dipyrrylmethene, 0.39 g., (2.2 mM),of zinc acetate dihydrate. and 0.67 g. of triethylamine was refluxedwith ml. of absolute ethanol for 2 hours, after which it was poured intoml. of cold water with stirring. The residue was removed by suctionfiltration, washed thoroughly with water, and dried in vacuo overDrierite at 60 C. Purification was accomplished by extracting thisresiude with absolute ethanol in a Soxhlet extractor for 48 hours. Therewas obtained 0.41 g. (66 percent) of the zinc complex of3,3',S-triphenyl-S'-o-hydroxyphenyldipyrrylmethene,

m.p. 300 C. )t 593 mp; e,,,,,,"""" 74,000 C=l .8 X 10" M (Found: C,70.65; H, 4.68; N, 4.83; Zn, 12.93. C.,,H,,N,0,Zn [-1 requires C, 70.24;H, 4.66; N,4.97; Zn, 11.60.)

EXAMPLE 8 A mixture of 0.48 g. (1 mM) of5,5'-bis-(o-hydroxyphenyl)-3,3-diphenyldipyrrylmethene, 0.24 g. (1.1 mM)of zinc acetate dihydra te, and 0.5 g. (5.0 mM) of triethylamine wasrefluxed with 50 ml. of absolute ethanol for 1 hour, after which it waspoured into 100 ml. of cold water with stirring. The residue was removedby suction filtration, washed thoroughly with water, and dried in vacuoover Drierite at 60 C. Purification was accomplished by extracting thisresidue with absolute ethanol in a Soxhlet extractor for 24 hours. Therewas obtained 0.36 g. (62.4 percent) of the zinc complex of3,3'-dipheny1-5,5-bis(o-hydroxyphenyl)dipyrrylmethene, m.p. 300 C. A613; 575 mp; e 60,000; 24,000 C=l .8 X M (Found: C, 67.57; H, 5.63; N,4.75; Zn, 10.97. C I-I,,N,O,Zn (l-1;,O)*"',O requires C, 68.30; H, 4.55;N, 4.83; Zn, 11.25.)

EXAMPLE 9 A mixture of 0.48 g. (1 mM) of5,S'-bis(o-hydroxyphenyl)-3,3-diphenyldipyrromethene, 0.25 g. (1 mM 10percent excess) of cobalt acetate tetrahydrate, and 1.0 g. (12.7 mM) ofpyridine in 50 ml. of absolute ethanol was refluxed for 1 hour, afterwhich it was cooled and diluted with 150 ml. of water. The greenprecipitate was removed by suction filtration, washed thoroughly withwater, dried in vacuo at 60 C. over Drieritie, and then extracted withabsolute ethanol. One recrystallization of the ethanol insolublematerial from pyridine ethanol (1:4) afforded 0.40 g. (58 percent) ofthe cobalt complex of 5,5'-bis(o-hydroxyphenyl)-3,3-diphenyldipyrrylmethene, m.p. 300' C. Anal. Calcd. for C, -,H ,N,O,Co:C, 74.30; H, 4.52; N, 8.07; Co, 8.48; Found: C, 74.21; H, 4.76; N, 8.03;Co, 8.55; it 665 my; e 25,000.

EXAMPLE [0 The copper complex of 5,5'-bis(o-hydroxyphenyl)3,3'-diphenylpyrrylmethene was prepared by substituting copper acetatefor the cobalt acetate in Example 6. Yield: 15.6 percent; m.p. 300 C.Anal. Calcd. for IC I-LMO CWPP] .2C,l-I,,OH: C, 70.30; H, 5.40; N, 4.43;Cu, 10.02; Found: C, 71.06; H, 4.24; N, 4.80; Cu, 9.74; It 651 mp; e37,500.

EXAMPLE 1 l The nickel complex of 5,5'-bis(o-hydroxyphenyl)3,3'-diphenyldipyrrylmethene was prepared in the same manner. Yield:32.2 percent; m.p. 300 C. Anal. Calcd. for [C;,; H ,N O-,Ni'H O .2H O:C, 66.90; H, 4.09; N, 5.73; Ni, 9.64; Found: C. 66.85; H, 4.10; N, 5.20;Ni, 9.94; A 680 mp; e 23,300.

EXAMPLE 12 A mixture of 0.51 g. (1.1 mM) ofS-o-hydroxyphenyl-3,3',5'-triphenyldipyrrylmethene and 0.5 g. (2.0

mM) of nickel acetate tetrahydrate in 50 ml. of dimethylformamide wasrefluxed for 1 hour, after which it was cooled and diluted with 150 ml.of ice water. The precipitate was removed by suction filtration, washedthoroughly with water, and dried in vacuo over Drierite at 60 C. Onepurification by dissolution in dimethylformamide and reprecipitationwith water afforded 0.56 g. (94.5 percent) of the nickel complex of5-o-hydroxyphenyl-3,3',5'-triphenyldipyrrylmethene, m.p. 300 C. Anal.Calcd. for C fl N O,Ni; C, 72.70; H, 4.94; N, 7.07; Ni, 9.90; Found: C,73.01; H, 4.84; N, 6.86; Ni, 9.82; A 544 (emax 16,200): 613 (19,000);718 13,200).

EXAMPLE 13 A mixture of 0.42 g. (1.5 mM) of5'o-hydroxyphenyl-3',3,5-trimethyldipyrrylmethene, 0.33 g. (1.5 mM 10percent excess) of copper acetate monohydrate. and 0.35 g. of pyridinein 50 ml. of ethanol was refluxed for 30 minutes, after which it waspoured into ml. of ice water. The crude complex was removed by suctionfiltration and washed thoroughly with water. One recrystallization frompyridine-ethanol gave 0.39 g. (62.3 percent) of the copper complex of5'-o-hydroxyphenyl-3 ,3 ,5-trimethyldipyrrylmethene, m .p. 249-250 C.

EXAMPLE 14 In a similar manner, using pyridine as ligand, the coppercomplex of 5'-o-hydroxyphenyl-3'-phenyl-3,5- dimethylpyrrylmethene wasprepared in 54 percent yield, m.p. 300 C., it (MeCell) 559 mp; e 53,900.

EXAMPLE 15 Using p-benzylpyridine as ligand, the nickel complex ofo-hydroxyphenyl-3'-pheny1-3,S-dimethylpyrrylmethene was prepared in 44.8percent yield, m.p. 278280 C., A (MeCell) 548 mu; e= 54,500.

EXAMPLE 16 Using p-benzylpyridine as ligand, the zinc complex of theabove dye (formula 5) was prepared in 75.6 yield,

m.p. 288289.5 C., it an (MeCell) 550 mp; e=

39,400; 506 mu; e 39,400.

EXAMPLE 17 Using pyridine as ligand, the cobalt complex of the above dyewas obtained, m.p. 286-290 C., A (MeCell) 540 mu; 5 17,800.

Elemental analyses of all of the metal complexes prepared in theillustrative examples confirmed that they were all 1:1 complexes, exceptfor the prior art 2:1 complex prepared in Example 6.

The novel dyes of this invention are fugitive, not being stable to lightin their non-complexed form for any appreciable period of time. However,the metal complexes of these dyes are of good light and chemicalstability. The transition metal complexes are appreciably more stablethan the non-transition metal complexes and hence are preferred.

The spectral absorption curves of these dyes show that they as a classpossess sharp peaks and narrow bands. Stated another way, these dyesprovide maxgions of the spectrum which in practical use would beregarded as unwanted absorption.

Other known dyes, e.g., the cyanine dyes, possess similar spectralabsorption characteristics, but are also characteristically bothfugitive and incapable of existing in a form possessing adequatestability. Hence, the present dyes are markedly superior in that theyare both stable in complexed form and possess brilliant spectralabsorption characteristics.

The spectral absorption curves of: (1) an illustrative dye of thisinvention, the copper-pyridine complex of the dye of formula 3; (2) astandard control magenta dye, 2[ p-( 2' ,5 -dihydroxyphenethyl)-phenylazo ]-4- isopropoxy-l-naphthol; and (3) a chromium-complexeddye, lnochrome Pink N, have been superposed in the graph of the drawingto illustrate the superior spectral absorption characteristicsof thedyes of this invention over representative useful dyes heretoforeemployed in the art, the numerals on the drawing corresponding to thoserecited above. Note the sharp peak and narrow band of the claimed dyes.

The spectral absorption curves were obtained by swabbing a solution ofthe dye onto a dyeable stratum such as would be employed in preparing aphotographic dye image. Reflectance curves were then run 7 with standardapparatus for this purpose.

The ratio of the maximum absorption (D,., at th? peak of the curve tothe minimum absorption (D,,,.,,) at a fixed point, 450 p. was calculatedfor each of the dyes, a conventional means of analyzing and comparingthe brilliance and quality of magenta dyes. The band width midwaybetween the D and D (half-band width) of the dyes were also calculatedfurther to compare the brilliance and sharp peaks of the dyes. This datais set forth below:

D- lD-i- Hllf-Band Width 1. Formula 3 7.3 518 to 584-66 2. ControlMagenta 3.1 460 to 59$ 135 3. lnochrome Pink N 3.3 473 to 590 1 17 Thestability of each of the three dyes to the degradative effects of lightwas evaluated in conventional manner by subjecting the respective stratacontaining them to tests under a Xenon arc at 128 F. and 31 percentrelative humidity. After 8 hours the dye of formula 3 had only faded 8percent while the control magenta had faded 39 percent, as calculated bycomparing the D, at the beginning of the test to the D after 8 hours.The chromium complex, Inochrome Pink N exhibited greater stability, butas noted above, did not possess as good a spectral absorption curve.

By way of recapitulation, dyes are known which have greater stabilitythan the claimed metal complexes. Dyes are also known, e.g., the cyaninedyes, which possess a brilliance and spectral absorption characteristicscomparable to the claimed dyes. The remarkable thing about the claimeddyes is thus not each individual trait alone, but the combination ofboth. Typically, the narrow band, sharp peak brilliant dyes are fugitiveor unstable and are not capable of existing in a form possessingstability adequate for most purposes, e.g., by complexing; whereas dyesof sufficient stability for the contemplated use, e.g., in colorphotography, do not ossess as fine spectralabsorption curyes. v

imum absorption over a narrow region of the visible spectrum and minimalabsorption elsewhere over re- The essence of the present invention,therefore, is providing a novel class of dyes which combine both ofthese qualities and qualifications.

Since certain changes may be made in the above product and processwithout departing from the scope of the invention herein involved, it isintended that all matter contained in the above description or shown inthe accompanying drawing shall be interpreted as illustrative and not ina limiting sense.

What is claimed is: V l A d ipyrrylmethene dye of the formula:

N on a .x on-1) Q wherein:

each R methyl, ethyl, phenyl or Z m'-i Q is methyl, ethyl,o-dihydroxyphenyl, methylphenyl, methoxyphenyl, methyl andmethoxy-substituted phenyl or an o-hydroxyphenyl radical containing amethoxy substituent, a methyl substituent, or both; each 2' is hydroxy,methyl or methoxy; m' is a positive integer from 1 to 3', and X ishydrogen or hydroxy, provided that where 0' does not compriseo-hydroxyphenyl or ohydroxyphenyl radical substituted as defined, X

must be hydroxy. 2. A 1.1 metal complex of a dye of claim 1. 3. A metalcomplex as defined in claim 2 wherein said metal is a transition metal.

4. A metal complex as defined in claim 1 wherein said metal is cobalt,nickel, zinc or copper.

5. A dye as defined in claim 1 wherein Q is methyl.

6. A dye as defined in claim 1 wherein Q is odihydroxyphenyl.

7. 3 ,3 ,5 '-tripheny1-5-o-hydroxyphenyldipyrrylmethene.

8. 3 ,3 '-dipheny1-S ,5 '-di-(o-hydroxypheny1) dipyrryl-i methene.

9. 5'-o-hydroxypheny1-3',3,5-trimethyldipyrrlmethene.

10. 3 ,3 '-dimethyl-S ,5 -di-o-hydroxyphenyldipyrryls ams W v 1 l.'-o-hydroxyphenyl-3 '-pheny1-3 ,S-dimethyldipyrrylmethene.

11A 1:1 metal 10.

13. A 1:1 metal complex of the dye defined in claim 1 1.

complex of the dye defined in claim with formic acid, trlethoxymethaneor benzoic acid.

2. A 1.1 metal complex of a dye of claim
 1. 3. A metal complex asdefined in claim 2 wherein said metal is a transition metal.
 4. A metalcomplex as defined in claim 1 wherein said metal is cobalt, nickel, zincor copper.
 5. A dye as defined in claim 1 wherein Q'' is methyl.
 6. Adye as defined in claim 1 wherein Q'' is o-dihydroxyphenyl. 7.3'',3,5''-triphenyl-5-o-hydroxyphenyldipyrrylmethenE. 8.3,3''-diphenyl-5,5''-di-(o-hydroxyphenyl) dipyrrylmethene. 9.5''-o-hydroxyphenyl-3'' ,3,5-trimethyldipyrrlmethene. 10.3,3''-dimethyl-5,5''-di-o-hydroxyphenyldipyrrylmethene. 11.5''-o-hydroxyphenyl-3''-phenyl-3,5-dimethyldipyrrylmethene.
 12. A 1:1metal complex of the dye defined in claim
 10. 13. A 1:1 metal complex ofthe dye defined in claim
 11. 14. A 1:1 metal complex of the dye definedin claim
 12. 15. A 1:1 metal complex of the dye defined in claim
 13. 16.A 1:1 metal complex of the dye defined in claim
 14. 17. A process forpreparing a symmetrical dye of formula 1 comprising the step of reactinga compound of the formula: with formic acid, triethoxymethane or benzoicacid.